Gearing.



UNITED sTATEs PATENT oEEroE.

HENRY C. WALTER, OF BRIDGEPORT, CONNECTICUT, ASSIGNOR TO THE LOCOMOBLECOMPANY F AMERICA, OF NEW YORK, N. Y., A CORPORATION OF WEST VIRGINIA.

GEARIN G.

To all whom it may concern Be it known that I, HENRY C. W'ALTER, acitizen of the United States, and a resident of Bridgeport, county ofFairfield, and

State of Connecticut, have invented an Improvement in Gearing, of whichthe fol- .lowing description, in connection with the accompanyingdrawings, is a specification, like characters on the drawingsrepresenting like part-s.

This invention relates to toothed gearing,

and is more especially concerned with bevel gearing of a special type,which is characterized by its practically noiseless operation, and theabsence ofend thrust.

My invention will be best understood by reference to the followingspecification, when taken in connection with the accompanying drawingsof one specific embodiv ment thereof, while its scope will be moreparticularly pointed out in the appended claims.

In the drawings: Figure 1 is a plan of la portion of a bevel gearand apinion em? bodying myiinvention; Fig. 2 is an elevation of the same,viewed from the outer end of the pinion; Fig. 3 is a sectional view,- online 3- 5i of Fig. 2, looking toward the left; and Fig. 4 is a layout ordiagram representingthe mode of laying out the tooth vcurve on thedevelopment of the pitch gear. c

It is well known that bevel gears of the common spur type,- hav-ingstraight' teeth, are apt tobe noisy in action, especially after $5having become somewhat worn, and attempts have heretofore been made toobviate this objectionable effect by the use of her- 'ringbone teeth,and by the use of the sovcalled spiral, or skew-cut, form of tooth.

40 Both of these expedients, however, involve seriously objectionablefeatures. The herringbone gear is difficult, aswell as expensive, tolmake, and 4is weak along the median line of the gear face, while theso-called spiral or skew-cut bevel gear causes an end thrust on itsbearings, with consequent wear and loss of power. Both of theseobjections are overcome in the gears which form the subject matter ofthis application, and which I will now describe. 'Y

Referring to the drawing, and to the embodiment of my invention which Ihave selected for illustration, I have there shown .avbevel gear 5, anda pinion 6, whose pitch' tacones have common axis A., white the lineSpecification of Letters Patent.

Application filed April 19, 1915. Serial No. 22,231.

' Patented 12111.23, 1917.

A-B in Fig. 3 represents an element common to the rolling surfaces ofthe two pitch cones. In other words, the line A-B rep= resents the lineof contact of the two imaginary cones.l

The gear 5 is provided with teeth 7, and the pinion 6 with teeth 8,whose pitch and width of face may be suitable for the nature ofthe workto be performed, and the power to be transmitted. It is deemedunnecessary here to discuss the dimensions of the teeth, and the methodemployed in designing the form and angle of the tooth flank, since thesematters are well known tothose skilled in the art, and should require nofurther comment. It should be noted, however, that the teeth are ofsubstantiallyv uniform depth from end to end (Fig. 3), this being animportant feature of my'invention. rlhis I regard as a mattei' ofconsiderable practical importance, because not only is the cutting ofthe teeth greatly simplified, but great additional strength is attained.The spaces between the teeth will, of course, be provided with suitableclearances at the top and root thereof, as indicated in'F ig. 3, andthese clearance spaces also are preferably of 'substantially uniformdepth from end to end.

Referring to Fig. 4, I have there shown a diagram representinggraphically the laying out of the tooth curve on the development of theface of the gear.

end toend on an arc of a circle, andv that the same radius is used forboth sides of the tooth at the pitch line, or more correctly speaking,in the surface of the pitch cone. This radius may be represented by theline C-D in Fig. 4. The location of the center C, fromIA which thisradius is struck, may be arbitrarily selected withincertain limits,

l K It should bel here noted that each tooth is curved from the onlyessential, however, being that the l point of tangeiicy E of the arc tothe radial.

.line [KQ-F, drawn from vthe cone center (Fig. 4), shall be intermediatethe ends lof the tooth,-thatis to say, it should lie within the face ofthe'gear.

It will be understood that when the point of tangency is located as justdescribed,v the` two portions of the tooth on opposite sides of thispoint exert thrusts in opposite directions respectively, so that onecounteracts l i the other in much the same sense that the opposedangular tooth surfaces of a herringbene type of gear oppose each other.In the f example selected for illustratiomthe' n center C, from whichthe arc on the radius is struck, is located in an arc struck -from thecenter A on a radius A-G. The latter radius will, in practice, bedetermined arbitrarily. In the presentA instance, it is such that thepoint of tangency What nearer the innerend of the tooth,- that is tosay, it is exactly midway between the ends of the tooth. The width ofthe face is indicated by the line H-I, intersectingr the two arcs whichrepresent the'outer and inner limits of the gear face. If the teeth ofthe gear are cut right-hand, so to speak, the teeth of the pinion willbe cut left-hand,- that `is to say, viewing the tace' of the gear andpinion as seen in Fig. 1, for example, the uppermost teeth of the pinionhave a curve E is located somewhich isopposite to that of the teetlrlofthe' gear. This is represented diagrammatically ft: in Fig. 4, by layingouta second arc'correspending toY the arc drawn on the radius C-D. Thisvsecond arm-for the purpose ot comparison, I have designated C-D, itscenter C being located within a circle struck on the radius A-G. Thedistance Jfrom the center C to the center C in Fig. Jr is such that thearcs -struck therefrom on the radii C-D and C-D intersect at a point Jin the circle struck from the center A on the radius A-B, and whichrepresents the outer cir'cle of the gear face. It will now beobservedthat the two arcs struck from the cen ters C and C haveanotherpoint of intersection K, which falls outside of the gear face whosewidth is represented by the line `HI. lAs before stated, however, thedistribution of the .arc of the tooth within the width of the gear faceisa matter of selection within certain limits already defined. the pointof'tangen'cy E is located somewhat nearer the inner circumference of thegear face than the outer, with the result that inward pressure of theteeth is very slightly greater than the outer pressure, the tendencytherefore being to move the pinion toward the center of the Althoughthis is not at all necessary, been done'in the present instance with'gear; it has aview flanks of the terminal portions of the teeth. This isa matter of judgment according to the circumstances of the particularcase, It is Vfound in practice, however,-that the thrusts are opposed,or balanced in such a manner that the gears will run and transmit thedesired amount of power, wlth actually1 Copies o! this patent may beobtained for ave' cents each, by adaressing the C4D "the latter mayconstitute in effect .a Heating v cle whose pointl of tangency tobetterdistributing the wearon .the

no thrust bearings for the pinion. In fact,

member. It will thus be readily appreciated that the .highest possibleefficiency 'will be obtained from the gears, because the end thrust,with consequent wear and loss' of power, may be totally eliminated.

While I have herein shown and described one specific embodiment of myinvention for illustrative purposes, and have disclosed and discussed indetail the construction and arrangement incidental to one specificapplication thereof, it is to be understood that the invention islimited neither to the mere details or relative arrangement of parts,-

nor to its specific embodiment herein shown, but that extensivedeviations from the illus trated form or embodiment of the invention maybe made, without departing from the principles thereof;

Having thus described my invention, what I claim and desire by'LettersPatent to procure is: y

l. A pair of mating bevel gears whose teeth are each curved from end toend and formed on an arc of a circle whose point of tangency to a radialline drawn from the,

cone center is intermediate the ends ot' such tooth.

2. A pair' of mating` bevel gears whose teeth are each curved trom endto end and formed on an arc of a circle whose point of tangency to aradial line drawn from the cone center, is approximately midway betweenthe endsof such tooth.

3. A pair of mating bevel gears whose teeth are pot' substantiallyuniform depth from end to end and are each curved fromv end to end andformed on an arc of a circle whose point of tangency to a radial linedrawn Jfrom Athe cone center is intermediate the ends of such tooth."

al. As va new -article of manufacture, a

bevel gear whose teeth are each curved from end to end and are formed onan arc of a cirto a radial line drawn from the cone center of the gearis intermediate the ends of such tooth.

5. pair teeth are each curved from end to'end and formedon an arc of acircle'whose point of tangency toy a. radial line drawn from the conecenter is intermediate the inner end and the middle of such tooth.

In testimony whereof, I have, signed my name. Y

HENRY C. IVALTER.

Commissioner ofv atentl,

Washington, D. C.

of mating bevel gears whosel

